HATU is similar to HBTU, but reacts faster with less epimerization during coupling.1,2 HATU is preferred to HBTU in most rapid coupling protocols. HATU is utilized in the same manner as HBTU.3 As with HBTU, HATU should not be used in excess because it can react with the unprotected N-terminal and block further chain elongation. Used for synthesis of Nα-urethane protected β-amino alcohols and peptide alcohols.4 The aspartate epimerization can be controlled during the coupling of caspase specific tetrapeptides with aromatic amines by HATU as a coupling reagent and 2,4,6-tri-tert-butyl-pyridine (TBP) as additive.5 Also used in rapid automated derivatization of solid-phase supports for oligonucleotide synthesis.6